But people are also dynamic. We can realign quickly. Think about NFL linemen. They are bombarded with huge amounts of incoming force. Force that is coming in the form of very dynamic defensive tackles and ends. They are not holding static weight, they are pushing back people who are trying to get around them. If you want to talk about people who can push, and push ever changing forces from many different angles, NFL linemen are the best in the world.
I meant to give examples of sustaining a load where the rightmost of your pictures of increasing alignment is applied in practise. In my mind we're talking about sustaining a load, not pushing. I don't know much about the job of a NFL lineman. Is he supposed to stop and possibly bowl over or opponents who want to pass him to score?
Anyway, it's not really relevant to me. In my opinion, this ability to sustain a load is about being in a state where you don't align for a load from a specific direction. With push tests, uke can push on different parts of my body while I should not have to change anything. I try to be in a state where it does not matter where the push comes from, I'm just more stable when I'm "on", than when I'm "off".
My stability is different from different directions, because in some directions, body alignment happens to contribute to my stability, but IMO that's not what's being tested. What's being tested is the development of that which does not
rely on aligning my body to the direction of the force. Ideally, I would develop that other thing to a point that the contribution of body alignment is more or less inconsequential.